METHODE DE PREPARATION DE COMPOSES ETHANOIQUES FLUORES

PROCESS FOR THE PREPARATION OF FLUORINATED ETHANIC COMPOUNDS

Abrégé anglais

Abstract

The present invention provides a process for preparing an
fluorinated ethanic organic compound, which comprises:
reacting ethylene or a halogenated ethylenic compound with
uranium hexafluoride at a high temperature wherein the molar
ratio of ethylene or the halogenated ethylenic compound to
uranium hexafluoride ranges from 1:1 to 1.2:1.

Revendications

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What is claimed is:

1. A process for preparing a fluorinated ethanic organic
compound, which comprises: reacting ethylene or a halogenated
ethylenic compound with uranium hexafluoride at an elevated
temperature wherein the molar ratio of ethylene or the
halogenated ethylenic compound to uranium hexafluoride ranges
from 1:1 to 1.2:1.



2. The process of claim 1 wherein uranium hexafluoride
is diluted with an inert gas to a concentration of 20 to 100%
by volume.



3. The process of claim 2 wherein the inert gas is
selected from the group consisting of nitrogen, neon, argon
and fluorinated organic substances recycled from the reaction
system.



4. The process of claim 1 wherein the halogenated
ethylenic compound is selected from the group consisting of
trichloroethylene(C2HCl3), vinylidene chloride(C2H2Cl2), vinyl
chloride(C2H3Cl) and vinylidene fluoride(C2H2F2).




5. The process of claim 1 wherein the reaction of
ethylene or the halogenated ethylenic compound and uranium
hexafluoride is carried out by spraying the each component


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into the reaction system in a dispersed form and mixing and
contacting with each other.

Description

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PROCESS FOR THE PREPARATION OF FLVORINATED
. ETHANIC COMPOUNDS
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~ Field of the Invention
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The present invention relates to a process for preparing
. halogenated organic compounds; and, particularly to a process
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for preparing fluorinated ethanic compounds as a substitute
for CFC(chlorofluorocarbon) known to be destructive of the
ozone layer.

Backaround of the Invention
... .

There are a number of catalytic methods known for the
manufacture of fluorinated ethanic compounds. In the Proposal
; on Replacement of the Freons Destroying the Earth's Ozone
Layer with Ozone-Safe substitutes(Proceedings of All-Vnion
Conference on Refrigerating and Ozone-Safe Freons, Leningrad,
Ozone-Safe, 1989), there is provided a catalytic
. ..~
. 20 hydrofluorination for the preparation of fluorinated ethanic
.compounds, which uses antimony pentachloride as a catalyst in
liquid phase. The process is carried out at a temperature
;. ranging from 130 to 160C and a pressure ranging from 6 to 8
. kg/cm2G. The hydrofluorination in gaseous phase is carried
25 out at a temperature ranging from 150 to 350C on a catalyst.
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~ The prior methods for manufacturing a chlorofluorocarbon

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are generally based on the concept of replacing the chlorine
atoms with fluorine atoms.
For example, United States Patent No. 3,235,608(1966)
describes the fluorination process of chlorinated or fluoro-

chlorinated C1_12 hydrocarbons using uranium hexafluoride. Thefluorination is conducted by employing an inorganic fluoride
- catalyst such as fluorides of sodium, potassium, calcium, etc.
in a fluidized bed at a temperature ranging from 70 to 600C.
However, this method is not economical since it requires the
fluoride catalyst and an excess amount of uranium
; hexafluoride.
Further, United States Patent No. 3,382,049 describes a
. method of fluorinating trichloroethylene by employing uranium
hexafluoride. The main purpose of fluorination in this method
. 15 is to obtain uranium tetrafluoride, and, therefore, detailed
i information on organic compound, an auxiliary product, is not
provided. Furthermore, it is observed that any excess amount
: of uranium hexafluoride in the reactor may destroy the HCFC-
122a compound produced to CFC-113 compound.
The present inventors have pursued to solve the
. .,
above-mentioned problems; and, as a result, succeeded in
developing a method for preparing a fluorinated ethanic
compound, which can be less harmful to the ozone layer, by
lowering the excess amount of ethylenic compound as starting
.. 25 material to uranium hexafluoride as a catalyst a during the
.~i reaction between said two components.
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Summarv of the Invention

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. Accordingly, it is an object of the present invention to
~ provide an improved process for preparing a fluorinated
ethanic compound.
. In accordance with one aspect of the invention, there is
. provided a process for preparing a fluorinated ethanic
: compound, which comprises reacting ethylene or a halogenated
ethylenic compound with uranium hexafluoride at an elevated
temperature wherein the molar ratio of ethylene or the
halogenated ethylenic compound to uranium hexafluoride ranges
from 1:1 to 1.2:1.
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:S;: Detailed Description of the Invention
1 5
.:: In the process of the present invention, a fluorinated
i. organic compound is obtained by the fluorination of an
::: unsaturated ethylenic compound with uranium hexafluoride as
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shown in the following reaction formula(1):

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~ C = C~ + UF6 - ,CF - CF~ + ~F4 (1).
;.................. The halogenated ethylenic compo~lnd used ln the process of
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the present invention may lnclude trichloroethylene(C2HCl3),

. 25 vinylidene chlorlde(C2H2Cl2), vinylchloride(C2H3Cl), vinylidene -

fluoride(C2H2F2) and the like.

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The uranium hexafluoride may be diluted with an inert
diluent gas to make a concentration of 20-100% by volume for
the fluorination reaction, particularly for obtaining a stable
organic compound. The inert diluent may include nitrogen,
neon, argon and the like. As a diluent, the product, fluorine-
containing orgainc substances may be employed by recycling.
The choice of the limited molar ratios pertaining to
ethylene or the halogerJated ethylenic compound and uranium
hexafluoride to be fed is based on the fact that if uranium
hexafluoride is fed in an amount greater than the upper limit
, of the range, it makes the end product to be subjected to
degradation or decomposi-tion due to its interreaction with the
excessive uranium hexafluoride; and, if uranium hexafluoride
is fed in a smaller amount than the lower limit, it leads to
an overexpenditure of ethylene or the halogenated ethylenic
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compound and overall impairment of the final product.
. Ethylene or the halogenated ethylenic compound is
preferably fed into the reactor in a dispersed form, thereby
to improve the reaction efficiency and to provide the
desirable fluorination process in the flare. Accordingly, the
reaction of ethylene or the halogenated ethylenic compound
with uranium hexafluoride is carried out by spraying each
component into the reaction system and mixing and contacting
with each other.
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The fluorination reactlon ls conducted at an elevated

temperature ranglng from 80 to 400C, preferably 100 to 350C




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and under a slightly lower pressure than atmospheric pressure,
preferably -20mm H20.
The fluorinated organic compounds obtained in accordance
~ with the present invention have fluorines in both 1 and 2
positions of their chains.
The quantitative and qualitative analyses of the
compounds thus obtaind can be conducted by a gas
chromatography, IR spectrometry and NMR method(using H and F19)
. to determine their composition.
The following Examples illustrate the present invention
more specifically, without limiting the scope of the
;~ invention.
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Exam~le
In a reactor was continuously fed uranium hexafluoride
.~ gas as a fluorinating agent at a flow rate of 2.0 kg/hr (5.682
moles/hr) through a spray nozzle. Simultaneously, nitrogen
gas was charged into the reactor at a flow rate of 318.1
. Nl/hr(14.2 moles/hr) as a diluent.
, 20 Trichloroethylene was fed into the reactor through
; another spray nozzle while maintaining the molar ratio of
. .
trichloroethylene to uranium hexafluoride in the reactor at
1.08:1Ø The fluorination process was carried out as
` follows:
CHCl = CCl2 + UF6 ~ CHClF - CCl2F + UF4
(HCFC-122a)




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Fluorination was carried out at the temperature of 200C and
under a pressure of -20mm H20.
The reaction product mixture was passed through the
filter made of a porous nickel to remove uranium tetrafluoride
dusts and the remaining gas was condensed in a trap cooled
with liquid nitrogen to obtain the product as a liquid.
The content of 1,2-difluoro-trichloroethane contained in
the organic product was 88.7 wt% and that of 1,1-difluoro-
trichloroethane did not exceed 1 wt~.

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Exam~le 2

. . .
The procedures described in Example 1 above were repeated
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except that the molar ratio of trichloroethylene to uranium

~;;" 15 hexafluoride was maintained at 1.07:1Ø
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The content of 1,2-difluoro-trichloroethane in the
, organic product was 85 wt% and that of 1,1-difluoro-
trichloroethane did not exceed 1 wt~.

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Exam~le 3

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The procedures described in Example 1 above were repeated
except that the molar ratio of trlchloroethylene to uranium
;~ hexafluorlde was malntalned at 1.01:1Ø
The content of 1,2-difluoro-trlchloroethane ln the
organlc product was 81 wt~ and that of 1,1-difluoro-

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~ trichloroethane did not exceed 1 wt~.

.~ Exam~le 4

Similarly to Example 1, the fluorination process was
. carried out by using vinylidene chloride as the starting
- material as follows:

. . .
CH2 = CCl2 + UF6 ~ CH2F - CCl2F + UF4
(HCFC - 132C)
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: The molar ratio of vinylidene chloride to uranium hexa-
fluoride was maintained at 1.07:1Ø The fluorination
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: reaction was carried out at the temperature of 150CC and under
.15 a pressure of -20mm H20.
The content of 1,2-difluoro-dichloroethane in the organic
.. product was 65 wt% and that of 1,1-difluoro-dichloroethane did
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not exceed 1 wt%.
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Exam~le 5
:Similarly to Example 1, the fluorination process was
. carried out by uslng vlnyl chlorlde as the starting material
as follows:
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: 25 CH2 = CHCl + UF6 ~ CH2F - CHClF + UF4
. (HCFC - 142a)

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The molar ratio of vinyl chloride to uranium hexafluoride
was maintained at 1.06:1Ø The fluorination reaction was
:; carried out at the temperature of 120C and under a pressure
. of -20mm H20.
: 5 The content of 1,2-difluoro-chloroethane in the organic
product was 63 wt% and that of 1,1-difluoro-chloroethane did
. not exceed 1 wt%.
. . .
Exam~le 6
. Similarly to Example 1, the fluorination process was
carried out by using ethylene as the starting material as
~' follows:
.,
CH2 = CH2 + VF6 ~ CH2F - CH2F + UF4
(HFC - 152)

, The molar ratio of ethylene to uranium hexafluoride was
maintained at 1.08:1Ø The reaction was carried out at the
. 20 temperature of 100C and under a pressure of -20mm H20.
The content of 1,2-difluoro-ethane in the organic product
`~ was 54wt% and that of 1,1-difluoro-ethane did not exceed 1
," wt%.
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Example 7
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Similarly to Example 1, the fluorination process was
carried out by using vinylidene fluoride as the starting
material as follows:



CH2 CF2 + UF6 ~ CH2F - CF3 + UF4
(HFC - 13~a)

..
The molar ratio of vinylidene fluoride to uranium
. hexafluoride was maintained at 1.06:1Ø The reaction was
`. carried out at the temperature of 350C and under a pressure
of -20mm H20.
, The content of 1,1,1,2-tetrafluoroethane in the organic
15 product was 47 wt~ and that of 1,1,2,2--tetrafluoroethane did
not exceed 1 wt~.
As shown in the above Examples, in accordance with the
present invention, the fluorination of unsaturated ethylenic
organic compounds with uranium hexafluoride produces organic
: 20 compounds containing fluorines in the 1 and 2 positions of the
their chains in surprisinqly high yields, which has not been
possible hitherto.
The use of the present method has an added advantage in
that it provides a basically wasteless process. The fluoro-

. 25 organic isomers obtained have a smaller polarity, and,
therefore, a higher solublllty with respect to fats, oils,




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: etc. Besides, the process makes it possible to obtain uranium
- tetrafluoride.
While the present invention has been shown and descrlbed
with reference to the particular embodiments, it will be
apparent to those skilled in the art that many changes and
modifications may be made without departing from the spirit
... . .
and scope of the invention as defined in the claims.

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